You have to remove amdvlk - as long as it is installed, games use that and it is bad (compared to vulkan-radeon)
Also, try to play the game for 10-15 minutes as some disk caches need to be generated first, afterwards performance should be great.
that is really bad advice. In addition to the already mentioned cheating protection, that also tells developers that windoze versions are enough and that they can stop provide native builds. And performance of native builds is always better than protonified versions (at least on my 7700X RX6750XT machine, haven’t used anything else for over a year)
Edit: Kernel 6.6.3 contains many AMD GPU fixes and is in stable already, also, mesa 23.3.0 got released yesterday evening but is not in testing yet - both could also help as your GPU is rather new.